Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$221.76	9.621%	$243.0955	$243.10	$243.10	$243.10
Purchase #2	$205.61	11.529%	$229.3148	$229.31	$229.30	$229.30
Purchase #3	$40.58	10.755%	$44.9444	$44.94	$44.95	$44.90
Purchase #4	$42.86	13.866%	$48.803	$48.80	$48.80	$48.80
Purchase #5	$211.57	5.593%	$223.4031	$223.40	$223.40	$223.40
Purchase #6	$119.52	12.446%	$134.3955	$134.40	$134.40	$134.40
Purchase #7	$201.89	10.773%	$223.6396	$223.64	$223.65	$223.60
7 purchase totals =	$1,043.79		$1,147.5959	$1,147.59	$1,147.60	$1,147.50